An indirect attack typically uses a straight or solid stream flowing ______ gpm?

An indirect attack typically utilizes a straight or solid stream flowing between 120 to 180 gallons per minute (gpm) because this range provides an effective balance of reach, penetration, and cooling capacity when combating fires. In an indirect attack, the goal is to heat the combustion gases in the upper layers of the room, causing them to cool down and, in turn, reduce the temperature of the fire, ultimately leading to the fire being extinguished.

This particular flow rate is sufficient to create the necessary steam conversion when the water is introduced into the fire environment. When water in this range is used, it generates a significant steam conversion that can both lower the temperature and reduce flammable gases, creating a safer environment for firefighters to eventually make a direct attack if needed.

Using flow rates that are either significantly lower or higher than this range may not achieve the desired effects. Lower flow rates might not generate enough steam to affect the fire significantly, while higher flow rates might lead to excess water application and create hazardous conditions like flashover or overwhelming steam production that could impede visibility or create slip hazards.